Kinetic Theory of Matter

Section 11.1

It’s based on the idea that particles of matter are always in motion and that this motion has consequences.

Ideal Gas - is an imaginary gas that conforms perfectly to all the assumptions of the kinetic theory.

Kinetic-Molecular Theory of Gases:

Based upon 3 assumptions:

1. Gases consists of large numbers of tiny particles

- gases volume is 1000 times that of a liquid or solid

- most volume is empty space ; compressible

2. The particles of a gas are in constant motion, moving rapidly in straight lines in all directions, and thus possess kinetic energy.

3. The collisions between particles of a gas and between particles and container walls are elastic collisions.

Elastic collision - is one in which there is no net loss of kinetic energy.

- Kinetic energy is transferred between 2 particles during collisions total kinetic energy remains constant at constant temp. and pressure.

4. There are no forces of attraction or repulsion between the particles of a gas.

5. The average kinetic energy of the particles of a gas is directly proportional to the Kelvin temp. of a gas.

- The kinetic energy of a particle is given as

(formula)

Specific gases have the same mass - KE only depends on velocity

Temperature dependent - (KE & v)

increase temp - increase KE & v

decrease temp - decrease KE & v

graph on p. 317

At the same temperature -

lighter gases - higher average velocities than heavier gas

Samples of all gases have the same average kinetic energy value at the same temperature

Expansion - gases do not have a definite shape or volume - fill container (1 liter vs. 2 liter)

Fluidity - gas particles glide easily past one another. Gases flow like liquids - fluids

Low-Density - gases have 1/1000 the density of a liquid or a solid - the particles are further apart

Compressibility - under sufficient compression - volume of a gas can be decreased by 1000 times

Diffusion - the movement of particles from high to low concentration

-Rate depends on 3 properties: their speed, diameters, and the attractive forces between them.

Effusion - process by which gas particles under pressure pass through a very small opening from one container to another.

-Rates of effusion of different gases are directly proportional to their molecular velocities.

Real Gases - is a gas that does not behave completely according to the assumptions of the kinetic theory

- Kinetic theory holds true for noble gases and gases that do not have a high attraction for one another